The Evolution of Layered Protocol Stacks Leads to an Hourglass-Shaped Architecture

Executive Summary

The Internet protocol stack has a layered architecture that resembles an hourglass structure. The bottom and top layers tend to see frequent innovations, while the protocols at the center of the hourglass appear to be ossified. The authors propose EvoArch, an abstract model for studying protocol stacks and their evolution. EvoArch is based on few first principles about protocol stacks and their evolution in a competitive environment where protocols acquire value based on their products and compete with other protocols at the same layer. EvoArch produces the well-known hourglass structure of the TCP/IP stack from general initial conditions in a robust manner. It also explains how some protocols, such as TCP or IP, managed to survive much longer than other protocols at the same layers.